JP5687929B2 - Organic waste processing method and organic waste processing apparatus - Google Patents

Description

  The present invention relates to an organic waste treatment method and an organic waste treatment apparatus related to anaerobic digestion treatment such as sewage sludge treatment.

Conventional sewage such as general household wastewater is subjected to the following treatment in a sewage treatment plant.
The sewage sent to the sewage treatment plant is separated into supernatant liquid and sludge as sediment (hereinafter referred to as primary sedimentation sludge) in the first sedimentation basin after collecting large waste. The supernatant liquid is sent to the aeration tank, where aerobic treatment is performed by aerobic microorganisms. The treatment liquid that has been subjected to the aerobic treatment is separated into a supernatant and a precipitate in the final sedimentation basin.

The supernatant liquid in the final sedimentation basin is discharged as treated water.
Part of the sediment in the final sedimentation basin is sent to the aeration tank to promote aerobic treatment, while the other is treated as surplus sludge by the following two methods.
In the first treatment method of surplus sludge, moisture is removed in the dewatering step together with the initial settling sludge, and the final disposal such as incineration and landfilling of the dewatered surplus sludge and the first settling sludge is performed.

The second method for treating excess sludge is to perform the following anaerobic digestion treatment, followed by dehydration and final disposal such as incineration and landfill.
The conventional general anaerobic digestion treatment of sewage sludge consists of an initial sludge after concentration (precipitation) and surplus sludge that is a residue after treating the supernatant of the sewage with aerobic microorganisms. Is directly put into an anaerobic digestion tank for processing.

Here, the anaerobic digestion process in the anaerobic digestion tank is an intermediate temperature fermentation at 35 to 38 ° C. and the digestion days (the days of residence of the primary sludge and surplus sludge in the tank) are 20 to 30 days, and 50 to 55 ° C. And high-temperature fermentation with digestion days of 10-20 days.
In order to maintain the digestion temperature in the anaerobic digestion tank, heat is supplied from the outside into the anaerobic digestion tank for heating.

Recently, in order to improve the efficiency of the anaerobic digestion process, that is, to speed up the process, as a pre-process of the conventional anaerobic digestion process, a solubilization process technology such as heat, ozone, ultrasonic waves, mill crushing, etc. has been added. A method to increase sludge and reduce sludge after anaerobic digestion has appeared.
Among the solubilization techniques, heat treatment is promising, and the main method is digestion after first solubilizing sludge and excess sludge are mixed and heat solubilized.

Here, in order to perform heat solubilization, in order to make it the high temperature of 160-190 degreeC, it heats with saturated water vapor | steam. Therefore, at the time of heat solubilization, it is a high temperature of 160 to 190 ° C. and a high temperature and a high pressure of 1.7 to 2.0 atm (0.7 to 1.0 MPa).
Therefore, a decompression tank that decompresses after heat solubilization and a cooling device that cools to an appropriate temperature for anaerobic digestion treatment in an anaerobic digestion tank (35 to 38 ° C for medium temperature fermentation and 50 to 55 ° C for high temperature fermentation) are provided. ing.
As prior art documents related to the present application, there are the following Patent Documents 1 and 2.

Special table 2003-500208 gazette JP 2008-296192 A

By the way, in the above-mentioned first method for treating excess sludge, the amount of excess sludge after dehydration is large, and subsequent operations such as transportation are troublesome.
Moreover, fuel is required when burning the excess sludge after dehydration. On the other hand, it is difficult to secure a landfill site when surplus sludge after dewatering is landfilled as industrial waste. In addition, there is an inconvenience that residents near the landfill are disgusted.
Furthermore, there is a problem that the cost increases due to the large amount of excess sludge after dehydration.

The second method for treating surplus sludge has a disadvantage that the capacity of the digestion tank is large and the sludge reduction rate is low for that. In addition, the method of heat solubilization in the previous step of the anaerobic digestion treatment is inefficient in the use of heat energy because the first settled sludge that is easy to digest is also heat treated. Moreover, it is necessary to cool to the appropriate temperature of an anaerobic digestion process before digesting the heated thing for heat solubilization. Thus, since the heated thing is cooled again, energy efficiency is bad.
Further, a decompression tank for decompression after heat solubilization and a cooling device for cooling are required, and auxiliary equipment such as a heat exchanger for recovering the applied heat is also required. And the maintenance of these facilities is required and there exists a problem that the cost burden concerning this is large.

  In view of the above situation, the present invention can reduce energy, reduce costs without the need for equipment and maintenance, and reduce organic waste and efficiently recover energy. The purpose is to provide a waste treatment device.

In order to achieve the above object, the organic waste treatment method according to the first aspect of the present invention is configured to separately treat excess sludge after aerobic treatment of the organic waste and the initial settling sludge of the organic waste. An organic waste treatment method to treat, wherein the flow rate of the excess sludge is mixed with the first settling sludge in the anaerobic digestion treatment after the heat solubilization , the heat solubilization wherein the excess sludge heat between the primary sludge heat, the flow rate adjusting step of adjusting a predetermined flow rate such that the temperature range of suitable temperature for the anaerobic digestion process, a predetermined flow rate by the flow rate adjusting step after The heat solubilization process for heat solubilizing the surplus sludge adjusted to the above, and the extra sludge and the first settling sludge heat solubilized in the heat solubilization process do not require new energy for heating An anaerobic digestion step of performing the anaerobic digestion process.
Desirably, an appropriate temperature range for the anaerobic digestion treatment is a temperature range of about 35 to 38 ° C. which is a medium temperature fermentation or a temperature range of about 50 to 55 ° C. which is a high temperature fermentation, and the heat solubilization step is 120 to 190. It may be performed at a temperature of ° C.

  The organic waste disposal apparatus according to the seventh aspect of the present invention is an apparatus that realizes the organic waste disposal method according to the first aspect of the present invention.

  According to the organic waste processing method of the first aspect of the present invention and the organic waste processing apparatus of the seventh aspect of the present invention, since the heating energy of heat solubilization is used for the anaerobic digestion process, excess energy is used. Energy saving can be achieved without using it, and no equipment or maintenance is required.

The organic waste treatment method according to the second aspect of the present invention is the organic waste treatment method according to the first aspect of the present invention, wherein the flow rate adjustment step is performed so that the excess sludge has the predetermined flow rate. Adjust the sludge concentration.
The organic waste disposal apparatus according to the eighth aspect of the present invention is an apparatus for realizing the organic waste disposal method according to the second aspect of the present invention.

  According to the organic waste treatment method of the second aspect of the present invention and the organic waste treatment apparatus of the eighth aspect of the present invention, the flow rate of the excess sludge can be adjusted by adjusting the concentration of the excess sludge.

  The organic waste disposal method according to the third aspect of the present invention is the organic waste disposal method according to the first or second aspect of the present invention, wherein the flow rate adjusting step sets the flow rate of the excess sludge after the excess sludge. In the anaerobic digestion process, when the initial sludge is mixed with the crushed raw garbage, it is adjusted to a predetermined flow rate so as to be an appropriate temperature for the anaerobic digestion process, and the anaerobic digestion process is the heat solubilization process. The anaerobic digestion treatment is performed on the surplus sludge, the initial settling sludge and the crushed raw garbage that have been heat-solubilized in step (b).

  The organic waste disposal apparatus according to the ninth aspect of the present invention is an apparatus that realizes the organic waste disposal method according to the third aspect of the present invention.

  According to the organic waste processing method of the third aspect of the present invention and the organic waste processing apparatus of the ninth aspect of the present invention, the garbage can be decomposed together with the excess sludge and the initial settling sludge.

The organic waste processing method according to the fourth aspect of the present invention is the organic waste processing method according to any one of the first to third aspects, wherein the anaerobic digestion step is acid fermentation in which acid fermentation is performed. It is separated into a process and a methane fermentation process for performing methane fermentation.
The organic waste disposal apparatus according to the tenth aspect of the present invention is an apparatus for realizing the organic waste disposal method according to the fourth aspect of the present invention.

  According to the organic waste processing method of the fourth aspect of the present invention and the organic waste processing apparatus of the tenth aspect of the present invention, the anaerobic digestion step includes an acid fermentation step for performing acid fermentation and a methane fermentation step for performing methane fermentation. Therefore, the anaerobic digestion process can be efficiently performed because the treatment can be performed in an atmosphere suitable for each of the acid fermentation process and the methane fermentation process.

The organic waste treatment method according to the fifth aspect of the present invention is the digestion method according to any one of the first to fourth aspects of the organic waste treatment method of the present invention, wherein the anaerobic digestion process is performed in the anaerobic digestion step. A first solid-liquid separation step for solid-liquid separation of the post-organic waste, and a first circulation step for circulating the solid content separated in the first solid-liquid separation step to the anaerobic digestion step. Yes.
The organic waste disposal apparatus according to the eleventh aspect of the present invention is an apparatus that implements the organic waste disposal method according to the fifth aspect of the present invention.

  According to the organic waste processing method of the fifth aspect of the present invention and the organic waste processing apparatus of the eleventh aspect of the present invention, the solid content of the organic waste after digestion subjected to the anaerobic digestion process is applied to the anaerobic digestion step. Since it circulates, more methane gas can be recovered and the solid content of the organic waste after digestion can be further reduced.

The organic waste disposal method according to the sixth aspect of the present invention is the digestion method according to any one of the first to fifth aspects of the organic waste disposal method of the present invention, wherein the anaerobic digestion process is performed in the anaerobic digestion step. A second solid-liquid separation step for solid-liquid separation of the post-organic waste, and a second circulation step for circulating the solid content separated in the second solid-liquid separation step to the heat solubilization step. Yes.
The organic waste disposal apparatus according to the twelfth aspect of the present invention is an apparatus for realizing the organic waste disposal method according to the sixth aspect of the present invention.

  According to the organic waste processing method of the sixth aspect of the present invention and the organic waste processing apparatus of the twelfth aspect of the present invention, the solid content of the post-digestion organic waste that has been subjected to the anaerobic digestion process is subjected to the heat solubilization step. Since it circulates, more methane gas can be recovered and the solid content of the organic waste after digestion can be further reduced.

  According to the organic waste processing method and the organic waste processing apparatus of the present invention, new energy to be heated for anaerobic digestion is unnecessary, and after the organic waste is heat-solubilized. Costs can be reduced without the need for cooling facilities and maintenance, and efficient energy recovery can be achieved by reducing waste volume and increasing methane gas.

It is a conceptual diagram functionally showing a sewage treatment plant. It is a conceptual diagram which shows the organic sludge processing apparatus of Embodiment 1 concerning this invention functionally. It is a conceptual diagram which shows the organic sludge processing apparatus of Embodiment 2 concerning this invention functionally. It is a conceptual diagram which shows the organic sludge processing apparatus of Embodiment 3 concerning this invention functionally.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
FIG. 1 is a conceptual diagram functionally showing the sewage treatment plant 1.
Sewage (organic waste) such as household wastewater from general households and human waste is sent to the sewage treatment plant 1 shown in FIG.

  The sewage treatment plant 1 is aerobic in the first settling basin 2 for separating sewage into supernatant water and sludge (primary settling sludge), an aeration tank 3 for aerobically treating the supernatant water of the first settling pond 2, and the aeration tank 3. A final sedimentation basin 4 is provided for separating the treated aerobic digested organic waste into supernatant water and sediment.

The sewage sent to the sewage treatment plant 1 is first sent to the settling basin 2 after large dust is removed. In the first sedimentation basin 2, the sewage is separated into supernatant water and precipitated solid sludge by natural settlement (natural precipitation). This precipitated solid sludge is hereinafter referred to as initial settling sludge.
The supernatant water in the first sedimentation basin 2 is sent to the aeration tank 3 to be aerobically treated. Air is placed in the aeration tank 3, and the activity of aerobic microorganisms is activated.

In the aeration tank 3, the supernatant water containing organic matter is treated by digestion of aerobic microorganisms. The aerobic microorganisms are contained in the supernatant water sent to the aeration tank 3, but may be added to the aeration tank 3 separately.
The organic waste after aerobic digestion that has been aerobically treated in the aeration tank 3 is sent to the final sedimentation basin 4.

In the final sedimentation basin 4, the organic waste after aerobic digestion is separated into supernatant water and sediment (sludge) by natural settlement (natural precipitation). The sediment (sludge) in the final sedimentation basin 4 is mostly aerobic microorganisms that have increased by eating the organic matter of the supernatant water in the first sedimentation basin 2.
The supernatant water in the final sedimentation basin 4 is extracted as treated water and discharged.
On the other hand, the sediment in the final sedimentation basin 4 is sent to the branch paths p21 and p22 through the circulation path p1, a part of which is flow-controlled through the branch path p21 and sent to the aeration tank 3, and the others. The sediment is sent to the organic sludge treatment apparatus A1 as surplus sludge via the branch path p22, and the final treatment is performed.

<< Embodiment 1 >>
FIG. 2 is a conceptual diagram functionally showing the organic sludge treatment apparatus A1 of Embodiment 1 according to the present invention.
The organic sludge treatment apparatus A1 is an apparatus that adjusts the concentration of excess sludge and heat solubilizes it, and then directly puts it into the anaerobic digestion tank 7 together with easy-to-digest initial sludge and the like to perform anaerobic digestion treatment.
Specifically, the organic sludge treatment apparatus A1 directly digests primary settled sludge and raw garbage that are easily anaerobically digested, and excess sludge that is difficult to digest is heat energy (heat of 60 to 190 ° C. under saturated vapor pressure). To make it easy to digest as heat-solubilized surplus sludge that has been heat-solubilized, and then mixed with primary sludge and the like, and anaerobic digestion treatment.

In the organic sludge treatment apparatus A1, the excess sludge is mixed with the initial settling sludge, the concentration of the excess sludge is adjusted so that the temperature in the anaerobic digestion tank 7 is within a predetermined range, and the flow rate of the excess sludge is adjusted. ing.
That is, heating the first settling sludge at room temperature (for example, 10-25 ° C.) without cooling the high-temperature (for example, 60-190 ° C.) heat-solubilized surplus sludge after heat-solubilizing the excess sludge. In addition, the heat balance between the heat amount of the high-temperature heat-solubilized surplus sludge and the heat amount of the first-stage sedimentation sludge at room temperature falls within a predetermined range suitable for anaerobic digestion treatment in the anaerobic digestion tank 7. .

The organic sludge treatment apparatus A1 includes a concentration adjusting device 5 that adjusts the concentration of excess sludge, a heat solubilizing device 6 that heat-solubilizes the excess sludge after concentration adjustment, heat-solubilized heat-solubilized excess sludge, and first An anaerobic digestion tank 7 that performs anaerobic digestion processing such as initial sedimentation sludge from the sedimentation basin 2 (see FIG. 1) is provided.
The heat solubilizer 6 is a device for heat solubilizing excess sludge under high temperature and high pressure conditions.

  Specifically, the heat solubilizer 6 is connected to a container 6a into which excess sludge is charged, a pressure sensor (not shown) that measures the pressure and temperature in the container 6a, a temperature sensor, and a boiler (not shown). Then, a steam valve (not shown) for controlling the supply of steam into the container 6a, a pressure control valve 6b for controlling the pressure in the container 6a, and the pressure control valve 6b and the steam valve are controlled to control the container 6a. And a controller for controlling the inside to a predetermined temperature and a predetermined pressure. The pressure control valve 6b is controlled in its opening degree in order to maintain the atmospheric pressure in the heat solubilizer 6 and to reduce the pressure.

The heat-solubilizing device 6 is a continuous heat-solubilizing device that retains the supplied steam without wasteful discharge when supplying surplus sludge and discharging heat-solubilized surplus sludge obtained by heat-solubilizing surplus sludge. It is.
Here, the predetermined pressure in the container 6a is 0.2 MPa to 1.0 MPa, preferably 0.5 MPa to 0.8 MPa, and the predetermined temperature in the container 6a is 120 ° C. to 190 ° C., preferably 150 ° C. to 170 ° C. It is. Based on the temperature and pressure in the container 6a measured by the temperature sensor and the pressure sensor, the control unit opens and closes the steam valve and the pressure control valve 6b to obtain a predetermined pressure and a predetermined temperature. The surplus sludge thrown into is heat solubilized by hydrolysis.

  The concentration adjusting device 5 is used for the initial precipitation of the heat amount and normal temperature (for example, about 10 ° C. (winter) to about 25 ° C. (summer)) of the heat-solubilized high-temperature heat-solubilized surplus sludge sent to the anaerobic digestion tank 7. Adjust the concentration of the excess sludge sent to the heat solubilizer 6 so that the volume balance of the amount of heat of the sludge is within a predetermined temperature range suitable for anaerobic digestion without using equipment such as a heat exchanger. , A device for adjusting the flow rate. The predetermined temperature range is about 35 to 38 ° C. in the case of the above-described intermediate temperature fermentation and about 50 to 55 ° C. in the case of high temperature fermentation.

The concentration adjusting device 5 is provided with a concentration meter and a flow meter (not shown) for measuring the concentration and flow rate of excess sludge. By measuring the concentration and flow rate of the excess sludge in the concentration adjusting device 5 with a concentration meter and a flow meter, the control unit (not shown) allows the excess sludge to be sent from the heat solubilizer 6 to the anaerobic digestion tank 7. The concentration is adjusted and the flow rate of excess sludge is adjusted.
Concentration adjusting device 5 is a heat solubilization surplus performed in an anaerobic digestion tank 7 with heat of high temperature heat solubilization surplus sludge heat solubilized at a high temperature of 120 to 190 ° C. and heat of primary sedimentation sludge at room temperature. Use a suitable temperature for anaerobic digestion of sludge and primary sedimentation sludge.

For example, the temperature of the heat-solubilized surplus sludge heat-solubilized by the heat-solubilizing device 6 is 160 ° C., the temperature of the initial settling sludge is 10 ° C., and the heat-solubilized surplus sludge and the initial settling sludge in the anaerobic digestion tank 7 are used. When the suitable temperature for the anaerobic digestion treatment is 35 ° C., the flow rate F1 of the heat-solubilized excess sludge to the anaerobic digestion tank 7 and the flow rate F2 of the first settling sludge to the anaerobic digestion tank 7 are: It is calculated as follows from the balance of heat.
160 × F1 + 10 × F2 = 35 × (F1 + F2) (1)
From the formula (1), 5 × F1 = F2 (2)
The relationship is guided.

Therefore, since F1 = (1/5) × F2, the flow rate F1 of the heat-solubilized surplus sludge to the anaerobic digestion tank 7 is set to 1/5 of the flow rate F2 of the first settling sludge to the anaerobic digestion tank 7. I understand that
According to the relationship between the flow rate F1 of the heat-solubilized surplus sludge to the anaerobic digestion tank 7 and the flow rate F2 of the initial settling sludge to the anaerobic digestion tank 7 of the equation (2), the control unit anaerobically removes the heat-solubilized surplus sludge The flow rate F1 to the sexual digestion tank 7 and the flow rate F2 to the anaerobic digestion tank 7 of the first settling sludge are determined, and control is performed so that the flow rates are F1 and F2.

  Accordingly, the flow rate F1 of the heat-solubilized surplus sludge to the anaerobic digestion tank 7 is controlled by adjusting the concentration of the surplus sludge with the concentration adjusting device 5. That is, since the flow rate F1 of the heat-solubilized surplus sludge is adjusted by adjusting the concentration of the surplus sludge in the concentration adjusting device 5, the heat-solubilized surplus sludge may be controlled to the flow rate F1 in the relationship of the expression (2). .

  In addition to primary sludge and heat-solubilized surplus sludge, when anaerobic digestion treatment is performed on crushed garbage in the anaerobic digestion tank 7, the flow rate of the primary sedimentation sludge to the anaerobic digestion tank 7 and the crushed raw What is necessary is just to calculate similarly the flow volume which added the flow volume to the anaerobic digestion tank 7 of garbage as F2.

The concentration adjustment of the excess sludge in the concentration adjusting device 5 includes a method such as mixing dehydrated itself, partially undehydrated concentrated excess sludge, and dehydrated excess sludge.
The anaerobic digestion tank 7 is a tank for performing anaerobic digestion of the heat-solubilized heat-solubilized excess sludge and the initial sedimentation sludge.
The anaerobic digestion tank 7 (hereinafter referred to as digestion tank 7) is controlled by a control unit (not shown).

The digestion tank 7 agitates and mixes the heat-solubilized surplus sludge and the initial settling sludge already contained in the digestion tank 7 and the newly added high-temperature heat-solubilized surplus sludge and the room temperature initial settling sludge. And a methane gas recovery unit (not shown) for recovering the methane gas generated by the anaerobic digestion process.
The digestion tank 7 has a temperature distribution of the heat-solubilized high-temperature heat-solubilized surplus sludge and the normal settling sludge at room temperature, which are organic wastes in the digestion tank 7, by the stirring device 7 a disposed therein. It can be made uniform at a temperature suitable for anaerobic digestion.

  Although not shown, the digestion tank 7 includes a pH measuring instrument for measuring the pH value of the heat-solubilized surplus sludge and the first settling sludge, which are organic wastes in the digestion tank 7, and a pH adjuster in the digestion tank 7. As a pH adjuster capable of injecting an alkaline substance. In this case, the pH value of the organic waste in the digestion tank 7 can be monitored by the pH meter, and the pH value of the organic waste in the digestion tank 7 can be adjusted by the pH adjuster.

The stirring device 7a disposed in the digestion tank 7 may be the stirring blade 7a1 alone or the stirring blade 7a1 with a draft tube.
The stirring device 7a disposed in the digestion tank 7 has a cylindrical shape, here, a cylindrical shape, and is disposed inside the draft tube 7a2 and a draft tube 7a2 disposed so as to surround the central portion in the digestion tank 7. And a stirring blade 7a1 that is rotationally driven by a driving device (not shown).

  According to this stirring device 7a provided with a stirring blade with a draft tube, the stirring blade 7a1 stirs the heat-solubilized excess sludge and the first settled sludge of the organic waste in the digestion tank 7, thereby allowing the inside of the draft tube 7a2 to , A downward flow that is a flow from the top to the bottom is formed. Further, in the digestion tank 7, an upward flow that is a flow from the lower side to the upper side is formed outside (or around) the draft tube 7 a 2, so that the organic waste in the digestion tank 7 is entirely formed by the stirring device 7 a. The heat-solubilized excess sludge and the initial settling sludge of the product are stirred and flowed, and the temperature distribution of the heat-solubilized excess sludge and the initial settling sludge is promoted to be uniform.

  In addition, the digestion tank 7 is provided with a thermometer (not shown) that measures the temperature of the heat-solubilized excess sludge and the first settling sludge of the organic waste in the digestion tank 7. By feeding back the temperature measured by the thermometer, each of the heat-solubilized excess sludge (heat-solubilized organic waste) and the primary sedimentation sludge is set so that the organic waste in the digestion tank 7 reaches a predetermined temperature. The charging is controlled by the control unit as described above.

  Then, the high-temperature heat-solubilized excess heat-solubilized sludge and the first sedimentation sludge discharged from the heat-solubilization device 6 are introduced into the agitation device 7a or in the vicinity thereof in the digestion tank 7. Thereby, in the digestion tank 7, since the high-temperature heat-solubilized surplus sludge heat-solubilized and the primary sedimentation sludge at normal temperature can be stirred and mixed, the temperature of the organic waste in the digestion tank 7 Is promoted.

  For example, the high-temperature heat-solubilized excess sludge and the initial sedimentation sludge discharged from the heat-solubilization device 6 are introduced into the draft tube 7a2 or toward the inside of the draft tube 7a2, and more specifically, It is introduced in the vicinity of the stirring blade 7a1 or at a position overlapping with the stirring blade 7a1 when viewed from above and below. The position overlapping in the vicinity of the stirring blade 7a1 or in the vertical direction is a portion where the flow generated by stirring of the stirring blade 7a1 is fast, so that the heat of the heat-solubilized surplus sludge that has been heat-solubilized is more than the initial settling sludge at room temperature. It becomes possible to transmit efficiently.

Moreover, the following processes which are anaerobic digestion processes are performed by the digestion tank 7 by control of a control part.
Anaerobic digestion treatment consists of acid fermentation that produces organic acid (mainly acetic acid (CH ₃ COOH), other propionic acid (C ₂ H ₅ COOH), etc.) from excess sludge, and methane gas (CH ₄ ) from organic acid. There are two steps with methane fermentation to produce carbon dioxide (CO ₂ ).
When the two processes of the anaerobic digestion process are performed in parallel in the single digestion tank 7, the acid fermentation process and the methane fermentation process are performed in parallel.

  Then, the said control part first, the temperature of 35-38 degreeC (medium temperature fermentation) or 50-55 degreeC (high temperature) is used for the heat-solubilization surplus sludge and primary sedimentation sludge which are the organic waste in the digestion tank 7. Fermentation), and maintained for 7 to 30 days so that the pH value is 6.5 to 8.5.

In addition, when the temperature of the heat-solubilized surplus sludge and the initial settling sludge in the digestion tank 7 falls below a predetermined temperature, the organic waste in the digestion tank 7 is newly introduced by adding the heat-solubilized surplus sludge. Increase the temperature. On the other hand, when the temperature of the heat solubilized surplus sludge and the initial settling sludge in the digestion tank 7 exceeds a predetermined temperature, the temperature of the organic waste in the digestion tank 7 is newly introduced by adding the initial settling sludge. Is lowered.
In addition, when the temperature in the digestion tank 7 is 50-55 degreeC, the processing speed of a methane fermentation process has a 2 times processing capacity compared with the case where temperature is 35-38 degreeC.

Next, an organic sludge treatment method (organic waste treatment method) using the organic sludge treatment apparatus A1 will be described.
The organic sludge treatment method using the organic sludge treatment apparatus A1 has a concentration adjustment step (flow rate adjustment step), a heat solubilization step, and an anaerobic digestion step.

  In the concentration adjustment step, the initial settling sludge (approximately 10 to 25 ° C.) and the high-temperature heat-solubilized surplus sludge (120 ° C. to 190 ° C., preferably 150 ° C. to 170 ° C.) mixed in the digestion tank 7 are mixed. In this case, the flow rate is adjusted by adjusting the concentration of the excess sludge in the concentration adjusting device 5 so as to obtain an appropriate temperature that is anaerobically digested with the amount of heat.

  That is, the flow rate of surplus sludge is adjusted by adjusting the concentration of surplus sludge in the concentration adjusting device 5, and the flow rate of heat-solubilized surplus sludge heat-solubilized by the heat-solubilizing device 6 in the digestion tank 7 is digested. When the initial settling sludge and heat-solubilized surplus sludge are mixed in the tank 7, the temperature is appropriate for anaerobic digestion (about 35 to 38 ° C for medium temperature fermentation, about 50 to 55 ° C for high temperature fermentation). I am doing so.

  Specifically, as described above, for example, the temperature of the heat-solubilized surplus sludge heat-solubilized by the heat-solubilizing device 6 is 160 ° C., and the temperature of the initial settling sludge is 10 ° C. When the appropriate temperature for the anaerobic digestion treatment of the heat-solubilized surplus sludge and the primary sedimentation sludge is 35 ° C., the flow rate F1 of the heat-solubilized surplus sludge to the digestion tank 7 and the flow rate F2 of the primary sedimentation sludge to the digestion tank 7 are: Since it is expressed by equation (2) using equation (1) and F1 = (1/5) × F2, the flow rate F1 of the heat-solubilized surplus sludge to the digestion tank 7 is set as the digestion tank for the initial sedimentation sludge. The flow rate F2 to 7 may be 1/5. In addition, when thrown into the digestion tank 7, the flow rate which added the flow volume to the anaerobic digestion tank 7 of initial sludge and the flow rate to the anaerobic digestion tank 7 of the shredded garbage is F2 when thrown into the digestion tank 7. And it is sufficient.

Therefore, in the concentration adjustment step, the flow rate F1 of the heat-solubilized surplus sludge to the digestion tank 7 with respect to the flow rate F2 of the initial settling sludge to the digestion tank 7 is adjusted by adjusting the concentration of the excess sludge in the concentration adjusting device 5. .
By this concentration adjustment process, the temperature of the primary sedimentation sludge and the heat-solubilized surplus sludge in the digestion tank 7 becomes an appropriate temperature for the anaerobic digestion process, so that the anaerobic digestion process is performed efficiently.

In the heat solubilization process, the excess sludge which is difficult to perform the anaerobic digestion process in the subsequent process is heat solubilized in the heat solubilization apparatus 6 controlled to a high temperature and a high pressure, and the anaerobic digestion process is performed in the anaerobic digestion process. It is a process for making it promoted.
The inside of the heat solubilizer 6 is steamed from a boiler (not shown), and the pressure is 0.2 MPa to 1.0 MPa, preferably 0.5 MPa to 0.8 MPa, and the temperature is 120 ° C. to 190 ° C., preferably 150 It is controlled to a high temperature and high pressure of ℃ to 170 ℃.

  Excess sludge is continuously supplied into the high-temperature, high-pressure heat solubilizer 6 and heat solubilized. Thereby, the heat-solubilized surplus sludge (heat-solubilized organic waste) in which the surplus sludge is heat-solubilized can be obtained in the heat-solubilizing device 6.

Moreover, when discharging the heat-solubilized excess sludge heat-solubilized in the heat-solubilizing device 6, in order to control the temperature in the heat-solubilizing device 6 to a predetermined temperature, The amount of steam supplied to the heat solubilizer 6 is controlled according to the supply amount of excess sludge and the temperature in the heat solubilizer 6.
The anaerobic digestion process includes two processes, an acid fermentation process and a methane fermentation process, and is performed in the digestion tank 7.

  Since the two processes of acid fermentation and methane fermentation included in the anaerobic digestion process are performed simultaneously in a single digestion tank 7, heat solubilized surplus sludge (heat solubilized organic waste) It supplies in the digestion tank 7, and maintains in the digestion tank 7 for 7 to 30 days so that temperature may become 35-38 degreeC or 50-55 degreeC, and pH value may be 6.5-8.5. Thereby, the acid producing bacteria and the methanogenic bacteria can be grown and maintained in the digestion tank 7.

Then, acid fermented organic waste (acetic acid (CH ₃ COOH), propionic acid (C ₂ H ₅ COOH)) undergoes methane fermentation to generate methane gas (CH ₄ ) and carbon dioxide (CO ₂ ), The solid content will decrease.
The methane gas generated by anaerobic digestion is recovered by a methane gas recovery device (not shown) provided in the digestion tank 7 and supplied to a boiler or the like.

The post-digestion organic waste, which is an organic waste that has been subjected to an anaerobic digestion process, is separated into moisture (dehydrated filtrate) and solids (dehydrated sludge cake) by a dehydration apparatus (not shown). Are processed equally.
The dewatered sludge cake is dried by a drying device and incinerated, or is carried out of the organic sludge treatment apparatus A1 and composted or landfilled. The dehydrated filtrate that has been dehydrated is returned to, for example, an activated sludge treatment plant of a water treatment system that performs activated sludge treatment.

As described above, according to the organic sludge treatment method using the organic sludge treatment apparatus A1 of Embodiment 1, it is not necessary to use extra energy and to install an auxiliary device such as extra heat exchange. Therefore, energy consumption in the organic sludge treatment apparatus A1 is small, and equipment and its maintenance are not required. For example, thermal energy is reduced by about 20% compared to the conventional case.
In addition, since no equipment or maintenance is required, the cost can be reduced.

Furthermore, since excess sludge becomes easy to digest, the number of digestion days can be shortened compared with the conventional one (digestion days of 1/2 to 1/4 of the conventional one).
In addition, it is possible to reduce the amount of sludge generated from the sewage treatment plant 1 (30-50% reduction compared to the conventional), increase the digestion gas (methane gas) increase (10-30% increase compared to the conventional), and recover energy. Yes.
Therefore, a low-cost organic sludge treatment apparatus A1 that efficiently processes excess sludge that consumes less energy and does not require equipment and maintenance can be obtained.

<< Embodiment 2 >>
Next, an organic sludge treatment method (organic waste treatment method) using the organic sludge treatment apparatus A2 of Embodiment 2 will be described.
FIG. 3 is a conceptual diagram functionally showing the organic sludge treatment apparatus A2 of Embodiment 2 according to the present invention.

The organic sludge treatment apparatus A2 of the second embodiment includes an acid fermentation tank 27 that performs an acid fermentation process that easily ferments the anaerobic digestion tank 7 of the first embodiment at a high temperature (for example, about 60 ° C.), and a low temperature (for example, , About 35 ° C.) and a methane fermentation tank 28 that performs a methane fermentation process that is easy to ferment.
Since the other configuration is the same as that of the first embodiment, the same components as those of the first embodiment are denoted by reference numerals in the 20th order, and detailed description thereof is omitted.

The acid fermenter 27 includes a controller, a pH meter, a pH adjuster, a thermometer, and a stirring device 27a.
The acid fermenter 27 includes a thermometer that measures the temperature of the heat-solubilized excess sludge and the first settled sludge of the organic waste in the acid fermenter 27, and the control unit controls the organic waste in the acid fermenter 27. The introduction of the heat-solubilized surplus sludge and the initial sedimentation sludge is controlled so that (the heat-solubilized surplus sludge and the initial sedimentation sludge) have a predetermined temperature.

  Specifically, heat-solubilized surplus sludge (temperature 120 ° C. to 190 ° C., preferably 150 ° C. to 170 ° C.) and primary sedimentation sludge (for example, temperature 10 ° C. to 25 ° C.), which are organic wastes in the acid fermentation tank 27. The flow rate F21 of the heat-solubilized surplus sludge and the flow rate F22 of the first settling sludge are controlled in order to obtain a predetermined temperature suitable for acid fermentation (for example, about 60 ° C.).

Thereby, the heat-solubilized excess sludge (heat-solubilized organic waste) (temperature 120 ° C. to 190 ° C., preferably 150 ° C. to 170 ° C.) sent from the heat solubilizer 26 to the acid fermentation tank 27 is subjected to acid fermentation. For heating the heat-solubilized excess sludge (heat-solubilized organic waste) and the primary sedimentation sludge in the tank 27 to a temperature suitable for acid fermentation in anaerobic digestion (for example, about 60 ° C.). It can be a heat source.
The flow rate F21 of the heat-solubilized excess sludge heat-solubilized in the acid fermenter 27 and the flow rate F22 of the first settled sludge to the acid fermenter 27 are as follows, similar to the equations (1) and (2): Is calculated as follows.

For example, the temperature of the heat-solubilized surplus sludge heat-solubilized by the heat-solubilizing device 26 is 160 ° C., the temperature of the initial settling sludge is 10 ° C., and the heat-solubilized surplus sludge and the initial settling sludge in the acid fermentation tank 27 are used. When the suitable temperature of the anaerobic digestion treatment is 60 ° C., the flow rate F21 of the heat-solubilized excess sludge heat-solubilized in the acid fermentation tank 27 and the flow rate F22 of the first settling sludge to the acid fermentation tank 27 are as follows: Is calculated as follows.
160 × F21 + 10 × F22 = 60 × (F21 + F22) (3)
From the formula (3), 2 × F21 = F22 (4)
The relationship is guided.

Therefore, since F21 = (1/2) × F22, the flow rate F21 of the heat-solubilized surplus sludge to the acid fermentation tank 27 may be ½ of the flow rate F22 of the first settling sludge to the acid fermentation tank 27. I understand that.
In addition to the initial settling sludge and the heat-solubilized surplus sludge, when anaerobic digestion treatment is performed on the crushed garbage in the acid fermentation tank 27, the flow rate of the first settling sludge to the acid fermentation tank 27 and the crushed garbage What is necessary is just to calculate similarly the flow volume which added the flow volume to the acid fermenter 27 as F22.
Thus, the heat energy consumed can be reduced by effectively using the heat of the high-temperature heat-solubilized surplus sludge.

And it can control to the conditions suitable for each process of an acid fermentation process and a methane fermentation process, and an efficient anaerobic digestion process is attained.
In this case, however, the temperature is adjusted to 40 to 90 ° C. and then charged into the methane fermentation tank 28. The methane fermentation tank 28 may require a heat exchanger or the like for setting the temperature of the organic waste in the methane fermentation tank 28 to a predetermined temperature (for example, about 40 ° C.).

The stirring apparatus 27a for acid fermentation arranged in the acid fermentation tank 27 may be only the stirring blade 27a1 or the stirring blade 27a1 with a draft tube.
The stirring device 27a for acid fermentation in the case of a stirring blade with a draft tube corresponds to the stirring device 7a of FIG. 2 and is cylindrical, here cylindrical, and is disposed so as to surround the central portion in the acid fermentation tank 27. A draft tube 27a2, and a stirring blade 27a1 that is driven to rotate by a driving device (not shown) and disposed inside the draft tube 27a2.

  Then, the high-temperature heat-solubilized excess sludge (heat-solubilized organic waste), the primary sedimentation sludge, etc. discharged from the heat-solubilizer 26 are contained in the acid fermentation tank 27, in the acid fermentation stirrer 27a, or in the same. It is thrown in the vicinity. Specifically, as in the case of the stirring device 7a of FIG. 2 described above, it is introduced into the draft tube 27a2 or toward the inside of the draft tube 27a2, and more specifically, in the vicinity of the stirring blade 27a1 or It is introduced at a position overlapping the stirring blade 27a1 when viewed from above and below.

As a result, the position overlapping in the vicinity of the stirring blade 27a1 or in the vertical direction is a portion where the flow generated by stirring of the stirring blade 27a1 is fast, so the heat of the heat-solubilized surplus sludge that has been heat-solubilized is the initial settling sludge at room temperature. For example, it is possible to transmit more efficiently.
That is, according to the acid fermentation stirrer 27a, the organic waste in the anaerobic digestion tank 7 of the first embodiment is added to the heat-solubilized surplus sludge and the initial sedimentation sludge, which are organic wastes in the acid fermentation tank 27. It is possible to generate a flow similar to the flow of the heat-solubilized excess sludge and the initial settling sludge of the product, and the uniform temperature distribution of the organic waste in the acid fermentation tank 27 is promoted.

  In the two-tank digestion system in which the acid fermentation process and the methane fermentation process in the anaerobic digestion process are divided into separate acid fermentation tank 27 and methane fermentation tank 28, respectively, the acid fermentation process and methane fermentation are performed as follows. A process is performed.

  In the acid fermentation step, heat-solubilized surplus sludge (heat-solubilized organic waste) is supplied to the acid fermentation tank 27, and the control unit included in the acid fermentation tank 27 heats the organic waste in the acid fermentation tank 27. Solubilized excess sludge and primary sedimentation sludge are maintained for 1 to 2 days so that the temperature is 35 to 38 ° C, or 50 to 56 ° C, and the pH value is 5 to 7. Thereby, an acid producing microbe can be propagated and the state which grew can be maintained. Therefore, acid fermentation can be performed at an appropriate temperature, and acetic acid and propionic acid can be generated from heat-solubilized excess sludge and primary sedimentation sludge.

  In the next methane fermentation process, the organic waste subjected to acid fermentation is supplied to the methane fermentation tank 28 as a methane fermentation tank, and the control unit of the methane fermentation tank 28 converts the organic waste in the methane fermentation tank 28 into the methane fermentation tank 28. The temperature is 35 to 38 ° C., or 50 to 56 ° C., and the pH value is 6.5 to 8.5. Thereby, methanogenic bacteria can be propagated and the state which grew can be maintained. And the organic waste (acetic acid, propionic acid, etc.) acid-fermented in the acid fermenter 27 is methane-fermented in the methane fermenter 28 to generate methane gas and carbon dioxide, thereby reducing the solid content. .

According to the organic sludge treatment apparatus A2 of the second embodiment, the acid fermentation process and the methane fermentation process of the anaerobic digestion process are separated, and the treatment is performed at temperatures suitable for the acid fermentation process and the methane fermentation process, respectively. It is possible to efficiently decompose wastes (heat solubilized surplus sludge, primary sediment sludge, raw garbage, etc.). Therefore, an anaerobic digestion process can be performed effectively.
In addition, the same effects as those of the first embodiment are obtained.

<< Embodiment 3 >>
Next, an organic sludge treatment method (organic waste treatment method) using the organic sludge treatment apparatus A3 of Embodiment 3 will be described.
FIG. 4 is a conceptual diagram functionally showing the organic sludge treatment apparatus A3 of Embodiment 3 according to the present invention.

In addition to the configuration of the organic sludge treatment apparatus A2 of the second embodiment, the organic sludge treatment apparatus A3 converts the anaerobic post-digestion treatment sludge (post-digestion organic waste) discharged from the methane fermentation tank 38 into a solid content and a liquid content. The apparatus further includes a solid-liquid separation device 39 that separates (water) from solid and liquid, and a pipeline circulation line 31 that returns the solid content separated by the solid-liquid separation device 39 to the acid fermentation tank 37.
Since the other configuration is the same as that of the second embodiment, the same components as those of the second embodiment are denoted by reference numerals in the thirties and detailed description thereof is omitted.

The solid-liquid separation device 39 performs solid-liquid separation of the anaerobic post-digestion treated sludge (post-digestion organic waste) discharged from the acid fermentation tank 37 and the methane fermentation tank 38.
In the circulation line 31, the solid content obtained by solid-liquid separation of the organic waste after digestion that has been anaerobically digested in the acid fermenter 37 and the methane fermenter 38 in the acid fermenter 37 again is obtained. This is a pipeline for circulation. In addition, the circulation line 31 includes a circulation pump (not shown), and the solid content separated by solid-liquid separation is combined with the heat-solubilized surplus sludge (heat-solubilized organic waste) and the primary sedimentation sludge, and acid fermentation is performed. Circulate in the tank 37.

The stirring apparatus 37a for acid fermentation arranged in the acid fermentation tank 37 may be only the stirring blade 37a1 or the stirring blade 37a1 with a draft tube.
The stirring device 37a for acid fermentation in the case of a stirring blade with a draft tube corresponds to the stirring device 7a of FIG. 2 and is cylindrical, here cylindrical, and is disposed so as to surround the central portion in the acid fermentation tank 37. A draft tube 37a2 and a stirring blade 37a1 which is driven to rotate by a driving device (not shown) and is arranged inside the draft tube 37a2.

  The solid content of the high-temperature heat-solubilized excess sludge (heat-solubilized organic waste) discharged from the heat-solubilizer 36, the primary sedimentation sludge, and the organic waste after digestion from the circulation line 31 is acid fermentation. In the tank 37, it is injected | thrown-in in the stirring apparatus 37a for acid fermentation, or its vicinity. Specifically, as in the above-described stirring device 7a (see FIG. 2), it is charged into the draft tube 37a2 or toward the draft tube 37a2. More specifically, it is introduced in the vicinity of the stirring blade 37a1 or at a position overlapping with the stirring blade 37a1 when viewed from above and below.

  Thereby, the position overlapping in the vicinity of the stirring blade 37a1 or in the vertical direction is a place where the flow generated by the stirring of the stirring blade 37a1 is fast, so that the heat of the heat-solubilized surplus sludge that has been heat-solubilized is the initial settling sludge at room temperature. In addition, it is possible to more efficiently transmit to the solid content of the organic waste after digestion.

  That is, according to the stirring apparatus 37a for acid fermentation, the heat-solubilized surplus sludge and the initial settling sludge that are organic waste in the acid fermentation tank 37 and the solid content of the organic waste after digestion are Heat solubilization of organic waste in anaerobic digestion tank 7 It is possible to generate a flow similar to the flow of excess sludge and initial settling sludge, and uniform temperature distribution of organic waste in acid fermentation tank 37 Is promoted.

  The flow rate F31 of heat-solubilized surplus sludge that has been heat-solubilized in the acid fermentation tank 37, the flow rate F32 of the initial sludge into the acid fermentation tank 37, and the solid content of the organic waste after digestion from the circulation line 31 The flow rate F33 is calculated as follows.

For example, the temperature of the heat-solubilized surplus sludge heat-solubilized by the heat-solubilizing device 36 is 160 ° C., the temperature of the first sedimentation sludge is 10 ° C., and the solid content temperature of the organic waste after digestion from the circulation line 31 is When the temperature is 20 ° C. and the suitable temperature for the anaerobic digestion treatment of the solid content of the heat-solubilized surplus sludge and primary sediment sludge and the organic waste after digestion heat-solubilized in the acid fermentation tank 37 is 60 ° C. Flow rate F31 of the solubilized heat-solubilized surplus sludge to the acid fermentation tank 37, flow rate F22 of the first settling sludge to the acid fermentation tank 37, and acid fermentation of the solid content of the organic waste after digestion from the circulation line 31 The flow rate F33 to the tank 37 is calculated as follows, similarly to the equations (1) and (2).
160 × F31 + 10 × F32 + 20 × F33
= 60 × (F31 + F32 + F33) (5)
From equation (5), F31 = (1/10) × (5 × F32 + 4 × F33) (6)
The relationship is guided.

  Accordingly, since there is a relationship of F31 = (1/10) × (5 × F32 + 4 × F33), the flow rate F31 of the heat-solubilized surplus sludge to the acid fermentation tank 37 is changed to the flow rate of the first settling sludge to the acid fermentation tank 37. It is understood that the flow rate may be a sum of 1/2 of F32 and 2/5 of the flow rate F33 to the acid fermentation tank 37 of the solid content of the organic waste after digestion from the circulation line 31.

  In equations (5) and (6), the calculation is performed assuming that the heat capacity of the solid content of the organic waste after digestion is equivalent to the heat capacity of the heat-solubilized surplus sludge and the heat capacity of the primary sedimentation sludge. However, when the heat capacity of the solid content of the organic waste after digestion is different from the heat capacity of the heat-solubilized surplus sludge and the heat capacity of the first settling sludge, the F33 term may be multiplied by the heat capacity as a coefficient.

In addition to the solid content of primary sedimentation sludge, heat-solubilized surplus sludge and organic waste after digestion, when the crushed garbage is subjected to anaerobic digestion treatment in the acid fermentation tank 37, the primary fermentation sludge acid fermentation tank. What is necessary is just to calculate similarly the flow volume which added the flow volume to 37 and the flow volume to the acid fermentation tank 37 of the shredded garbage as F32.
Thus, the heat energy consumed can be reduced by effectively using the heat of the high-temperature heat-solubilized surplus sludge.

Next, an organic sludge treatment method using the organic sludge treatment apparatus A3 will be described.
In the organic sludge treatment method of Embodiment 3, the solid content separated in the solid-liquid separation step (first solid-liquid separation step) and the solid-liquid separation step is separated from the organic waste after digestion in the acid fermentation step of the anaerobic digestion step. The organic sludge treatment method according to the second embodiment is different from the organic sludge treatment method according to the second embodiment in that it includes a circulation step (first circulation step) for circulation. After passing through the solid-liquid separation step and the circulation step, the anaerobic digestion step of the solid content of the organic waste after digestion is performed.

In the solid-liquid separation step, the organic waste after digestion that has been anaerobically digested in the acid fermentation tank 37 and the methane fermentation tank 38 is separated into a solid content and a liquid content (moisture) by the solid-liquid separation device 39.
In the circulation step, the solid content of the organic waste after digestion separated in the solid-liquid separation step is circulated to the acid fermentation tank 37 by the circulation line 31, and the solid content of the organic waste after digestion is again anaerobically digested. It is a process for processing. The circulation process can be repeated any number of times.

According to the organic sludge treatment method using the organic sludge treatment apparatus A3 of Embodiment 3, the solid content of the post-digestion organic waste that has been anaerobically digested by the circulation line 31 is circulated in the acid fermentation tank 37. Heat-solubilized surplus sludge, primary settling sludge, etc. of toxic waste are repeatedly anaerobically digested.
According to this, compared with the case where an organic waste is anaerobically digested only once, more methane gas can be collect | recovered and solid content of an organic waste can be reduced more.

For example, the digestion rate of 50% can be digested by about 70 to 75% by returning it once. Moreover, digestion can be accelerated to about 80% by returning further.
In addition, the effect of the organic sludge processing method using the organic sludge processing apparatuses A1 and A2 of Embodiments 1 and 2 is similarly achieved.
Moreover, the effect of reducing the volume of organic waste and the recovery of methane gas increase in the order of Embodiments 1, 2, and 3.

  In the organic sludge treatment method using the organic sludge treatment apparatus A3 of Embodiment 3, the anaerobic digestion is performed by circulating the solid content of the organic waste after digestion into the acid fermentation tank 37 via the circulation line 31. Although the process is repeated, the organic sludge treatment apparatus A3 and the organic sludge treatment method of Embodiment 3 are not limited to this.

  For example, the circulation line may be circulated to the heat solubilizer 36 not via the acid fermenter 37 but via the circulation line 32 indicated by a two-dot chain line in FIG. In the case of this organic sludge treatment apparatus A3, the solid content of the organic waste after digestion is circulated to the heat solubilizer 36 (second circulation process) via the circulation line 32 (second solid-liquid separation process). Again, it is supplied into the acid fermentation tank 37 and the methane fermentation tank 38 through the heat solubilizer 36.

Therefore, in the organic sludge treatment method using the organic sludge treatment apparatus A3, the solid content of the digested organic waste subjected to the heat solubilization treatment is supplied to the acid fermentation tank 37 and the methane fermentation tank 38 again. Therefore, it becomes possible to collect more methane gas.
Or you may comprise so that the solid content of the organic waste after digestion may be circulated to the acid fermenter 37 and the heat solubilizer 36 via a circulation line.

  Similarly, in the organic sludge treatment apparatus A1 of Embodiment 1, a solid-liquid separation device is disposed after the anaerobic digestion tank 7 to separate the solid content obtained by solid-liquid separation of the organic waste after digestion, and the anaerobic digestion tank again. 7 and / or the heat solubilizer 6 may be circulated. Thereby, reduction of the volume of organic waste in organic sludge processing apparatus A1 and improvement of recovery of methane gas can be aimed at.

  In the formulas (1) to (6) of Embodiments 1 to 3, the heat capacity of the heat-solubilized surplus sludge, the heat capacity of the first settled sludge, the heat capacity of the crushed garbage, and the organicity after digestion from the circulation line 31 The case where the calculation is performed with the solid heat capacity equal to the waste is illustrated. However, when the heat capacities are different from each other, the heat capacity is multiplied by the coefficient of the heat capacity as a coefficient in each of the equations (1) to (6). The operation may be performed.

  In Embodiments 1 to 3, the flow rate for adjusting the excess sludge to an appropriate temperature for the anaerobic digestion process has been exemplified and described, but the adjustment is made directly with the excess sludge flow rate. It may be configured to do.

5, 25, 35 Concentration adjusting device (flow rate adjusting means)
6, 26, 36 Heat solubilizer (heat solubilization means)
7 Anaerobic digestion tank (anaerobic digestion treatment means)
27, 37 Acid fermentation tank (acid fermentation section, anaerobic digestion treatment means)
28, 38 Methane fermentation tank (methane fermentation section, anaerobic digestion treatment means)
31, 32 Circulation line (first circulation means, second circulation means)
39 Solid-liquid separation device (first solid-liquid separation means, second solid-liquid separation means)
A1, A2, A3 Organic sludge treatment equipment (organic waste treatment equipment)

Claims (14)

An organic waste processing method for separately processing surplus sludge after aerobic treatment of organic waste and primary sedimentation sludge of the organic waste,
When the surplus sludge is mixed with the first settling sludge in the anaerobic digestion after the subsequent heat solubilization, the flow of the excess sludge and the heat of the first settling sludge after the heat solubilization With a heat, a flow rate adjusting step for adjusting to a predetermined flow rate so as to be in a temperature range suitable for the anaerobic digestion treatment,
A heat solubilization step of heat solubilizing the excess sludge adjusted to a predetermined flow rate in the flow rate adjustment step;
An anaerobic digestion step of performing the anaerobic digestion process that does not require new energy to be heated with respect to the surplus sludge heat-solubilized in the heat-solubilization step and the initial settling sludge. A method for treating organic waste. The temperature range of the appropriate temperature of the anaerobic digestion treatment is a temperature range of about 35 to 38 ° C that is medium temperature fermentation or about 50 to 55 ° C that is high temperature fermentation,
The heat solubilization step is performed at a temperature of 120 to 190 ° C.
The organic waste processing method according to claim 1, wherein: The organic waste treatment method according to claim 1 or 2 , wherein the flow rate adjusting step adjusts the concentration of the excess sludge so that the excess sludge has the predetermined flow rate. The flow rate adjusting step is performed at a predetermined temperature so that the flow rate of the excess sludge becomes an appropriate temperature for the anaerobic digestion treatment when the excess sludge is mixed with the initially settled sludge and crushed garbage in anaerobic digestion treatment later. Adjusted to the flow rate of
The anaerobic digestion step performs the anaerobic digestion treatment on the surplus sludge heat-solubilized in the heat-solubilization step, the primary sedimentation sludge, and the crushed raw garbage. The organic waste processing method according to any one of claims 1 to 3 . The said anaerobic digestion process is isolate | separated into the acid fermentation process which performs acid fermentation, and the methane fermentation process which performs methane fermentation. The organic as described in any one of Claims 1-4 characterized by the above-mentioned. Waste disposal method. A first solid-liquid separation step for solid-liquid separation of the post-digestion organic waste subjected to anaerobic digestion in the anaerobic digestion step;
Any one of claims 1 to 5, characterized in that it comprises a first circulating step of circulating solids is solid-liquid separated by the first solid-liquid separation step to the anaerobic digestion step The organic waste disposal method as described in 2. A second solid-liquid separation step for solid-liquid separation of the post-digestion organic waste subjected to anaerobic digestion in the anaerobic digestion step;
Any one of claims 1 to 6, characterized in that it comprises a second circulation step of circulating solids is solid-liquid separated by the second solid-liquid separation step to the thermal solubilization step The organic waste disposal method as described in 2. An organic waste treatment apparatus for separately treating surplus sludge after aerobic treatment and primary sedimentation sludge of the organic waste,
When the surplus sludge is mixed with the first settling sludge in the anaerobic digestion after the subsequent heat solubilization, the flow of the excess sludge and the heat of the first settling sludge after the heat solubilization With heat, a flow rate adjusting means for adjusting the flow rate to a predetermined flow rate within an appropriate temperature range for the anaerobic digestion treatment,
Heat solubilizing means for heat solubilizing the excess sludge adjusted to a predetermined flow rate by the flow rate adjusting means;
Anaerobic digestion treatment means for performing the anaerobic digestion treatment that does not require new energy to be heated with respect to the surplus sludge heat-solubilized by the heat solubilization means and the initial settling sludge. Organic waste treatment equipment. The temperature range of the appropriate temperature of the anaerobic digestion treatment is a temperature range of about 35 to 38 ° C that is medium temperature fermentation or about 50 to 55 ° C that is high temperature fermentation,
The heat solubilization is performed at a temperature of 120 to 190 ° C.
The organic waste disposal apparatus according to claim 8, wherein: The organic waste treatment apparatus according to claim 8 or 9 , wherein the flow rate adjusting means adjusts the concentration of the excess sludge so that the excess sludge has the predetermined flow rate. The flow rate adjusting means has a predetermined flow rate so that the flow rate of the excess sludge becomes an appropriate temperature for the anaerobic digestion treatment when the excess sludge is mixed with the initially settled sludge and crushed garbage in anaerobic digestion treatment later. Adjusted to the flow rate of
The anaerobic digestion treatment means performs the anaerobic digestion treatment on the surplus sludge, the initial settling sludge and the crushed raw garbage that have been heat-solubilized by the heat-solubilization means. The organic waste disposal apparatus according to any one of claims 8 to 10 . The anaerobic digestion process means any one of claims 11 claim 8, characterized in that formed was separated in the methane fermentation unit for performing acid fermentation unit and the methane fermentation performing acid fermentation Organic waste processing equipment as described in 1. First solid-liquid separation means for solid-liquid separation of post-digestion organic waste subjected to anaerobic digestion treatment by the anaerobic digestion treatment means;
The first circulation means for circulating the solid content separated by the first solid-liquid separation means to the anaerobic digestion treatment means, The method according to any one of claims 8 to 12 , further comprising: The organic waste disposal apparatus according to the item. Second solid-liquid separation means for solid-liquid separation of the organic waste after digestion that has been anaerobically digested by the anaerobic digestion means;
Any one of said second solid-liquid separation second circulation means and claim 13 claim 8, characterized in that it comprises a a solid that was solid-liquid separation by means circulates said heat solubilizing means Organic waste processing equipment as described in 1.

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